A typical automotive vehicle having a spark ignition engine uses gasoline fuel. The vehicle includes an onboard fuel tank that defines a chamber in which the gasoline fuel is stored for use by the engine. The onboard fuel tank is refillable by offboard fuel pumps, such as the ones found at commercial gas stations.
A typical automotive onboard fuel tank is configured to cause an offboard pump to automatically stop delivering fuel to the tank when a predetermined volume of fuel is in the tank chamber. The predetermined volume is less than the volumetric capacity of the tank chamber. The remaining volume in the tank chamber is necessary to accommodate vapors that form from the liquid gasoline fuel in the tank.